"This trial is a significant first step by the PFRA, which will hopefully see the permanent establishment of a mystery shopping programme for private-site fundraising and will gather vital information on current standards," it said.

Peter Hills-Jones, chief executive of the PFRA, said in a statement that members had often asked the PFRA to expand its services.

"We have worked hard over the past decade to strengthen street and door-to-door fundraising, and we are now going one step further," he said.

Hills-Jones said the results of the trial would be made available to members "once it has provided evidence of success".